<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<h1>0</h1>


<script>
    let count = 0;
    let timer1 = setInterval(f, 1000);

    function f() {
        count++;
        let h = document.querySelector("h1");
        h.innerText = count;
    }
    let timer2 = setInterval(function (){
      console.log(count)
      if (count == 5){
        clearInterval(timer2)
      }
    },1000)

    setTimeout(function (){
      alert("时间到")
    },3000)

</script>


</body>
</html>